Image processing apparatus and image processing method

ABSTRACT

When converting image data constituted by a plurality of objects to data for an output device, color appearances of object images specified as a same output color are set so as to not vary even when their respective background colors vary. A color appearance model forward conversion section uses forward conversion of a color appearance model to calculate target appearance colors, which are targets of appearances of objects based on color information of the objects. A surrounding adaptive background color obtaining section generates surrounding adaptive background colors based on pixels around a pixel of interest for object images that have undergone rendering. Then, output pixel values of the pixel of interest are calculated by a color appearance model reverse conversion section using reverse conversion of the color appearance model based on the target appearance color and the surrounding adaptive background colors.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to image processing apparatuses and imageprocessing methods, and particularly relates to image processingapparatuses and image processing methods in which image dataconstituting objects is converted to data for output to an outputdevice.

2. Description of the Related Art

Heretofore, color matching technologies based on color appearance modelsthat take into account ambient light and observation conditions havebeen known as technologies aiming to achieve color appearance andcalorimetric accordance and metamerism using ambient light andobservation conditions and the like.

With these color-matching technologies, in a case where a certaindocument is to be observed under different observation conditions suchas ambient light and background colors, it is possible to achieveaccordance in the appearance of the displayed document and the printedoutput thereof in each of these respective observation conditions. Forexample, using a color appearance model such as CIECAM97s through to thesubsequently improved CIECAM02, color matching can be carried out givingconsideration to the appearance in a certain observation lightconditions on the output side. That is, accordance in appearance can beachieved under mutually different observation conditions (for example,see Japanese Patent Laid-Open No. 2000-040140).

However, with the aforementioned conventional technologies, there is afollowing problem in a case where a plurality of objects of an identicalcolor are present within a single sheet of a document even when underobservation conditions that have been specified in advance.

Namely, a plurality of object images arranged within the data of asingle document are influenced by the surrounding background color wherethe object images are arranged, thus changing the color appearance thatis perceived. Examples of this are shown in FIG. 3. In FIG. 3, objects301, 302, and 303 all have identical color values and are output asidentical colors, but have respectively different background colors.Consequently, the objects 301, 302, and 303 have undesirably differentcolor appearances due to the influence of their background colors. Forexample, the object 301 has a lighter background than the object 302,and therefore appears darker. And due to the gradations in thebackground of the object 303, the left side part of the object 303appears darker than the right side part. It should be noted thatdifferences in lightness according to grayscale data are illustrated inFIG. 3, but of course the same applies for chromatic color. Withchromatic colors, colors even more different in hue and lightness areperceived undesirably due to an influence of chromatic adaptation forsurrounding background colors.

With the aforementioned conventional technologies, it has not beenpossible to eliminate the influence of background color adaptation for aplurality of objects respectively having a same output color specifiedwithin a single sheet of a document and achieve accordance in appearanceamong these.

SUMMARY OF THE INVENTION

The present invention has been devised to address these problems and toprovide an image processing apparatus and an image processing methodhaving the following functionality, namely, causing accordance of mutualcolor appearance for a plurality of objects for which a same outputcolor has been specified within a same image even when these haverespectively different background colors.

Namely, an image processing apparatus, for converting an image having aplurality of objects, is provided with: a rendering unit configured toperform rendering on an image using object information of the pluralityof objects, a forward conversion unit configured to carry out forwardconversion processing of a color appearance model on color informationof the object in which a pixel of interest is contained, and calculatetarget color information of the pixel of interest, a surroundingadaptive background color obtaining unit configured to generatesurrounding adaptive background color information of the pixel ofinterest based on pixels around the pixel of interest in the object ofthe image that has undergone rendering, a reverse conversion unitconfigured to carry out reverse conversion of a color appearance modelon the target color information based on the surrounding adaptivebackground color information to calculate output color information, anda setting unit configured to set the output color information as colorinformation of the pixel of interest in the image that has undergonerendering.

For example, the object includes a color appearance accordanceattribute, and the reverse conversion means of the color appearancemodel controls whether or not to calculate output pixel values for theobject in response to the color appearance accordance attribute of theobject.

With the present invention configured as described above, it is possibleto cause accordance of mutual color appearance for a plurality ofobjects for which a same output color has been specified within a sameimage even when these have respectively different background colors.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a functional configuration of a colorconversion device according to one embodiment of the present invention.

FIG. 2A and FIG. 2B are a flowchart showing a color conversion processaccording to the present embodiment.

FIG. 3 is a diagram showing an example of display output affected by theinfluence of background color adaptation.

FIG. 4 is a diagram showing attributes of an object image according tothe present embodiment.

FIG. 5 is a diagram showing an example of contents of an objectinformation list according to the present embodiment.

DESCRIPTION OF THE EMBODIMENTS

The present invention is described in detail below based on preferredembodiments thereof with reference to the accompanying drawings. Itshould be noted that any configuration shown in the followingembodiments is merely an example and the present invention is notlimited to configurations shown in the diagrams.

Configuration of Color Conversion Device

In the present embodiment, consideration is given to an influence ofadaptation for background color (hereinafter, background coloradaptation) in output images when carrying out color conversion on inputimages for output in systems ranging from systems that perform displayon display devices such as displays to systems that perform print outputof document data containing object images.

FIG. 1 is a block diagram showing a functional configuration of a colorconversion device that executes color conversion processing according tothe present embodiment. First, in the present embodiment, document datahaving object images is input to an input section 101, which is an inputdevice. Then, ordinary rendering is executed on the document data by arendering section 102, and at the same time, attribute information ofthe object images is obtained by an object attribute informationobtaining section 103.

Then, by further executing forward conversion of a color appearancemodel based on attribute information of the object images in a colorappearance model forward conversion section 104, target appearancecolors indicating appearances of the colors in the final output imageaccording to the present embodiment are calculated.

A surrounding adaptive background color obtaining section 106 obtains asurrounding adaptive background color of the objects from the renderingimages obtained by the rendering section 102 to achieve accordance ofappearance for the objects. The obtaining of the surrounding adaptivebackground colors is carried out based on attribute information of theobject images obtained by the object attribute information obtainingsection 103.

Then, output colors are calculated by color appearance model reverseconversion according to the target appearance color values and thesurrounding adaptive background colors in a color appearance modelreverse conversion section 107. Then, an output color updating section108 overwrites output colors of object image regions using output colorscalculated by the color appearance model reverse conversion section 107and display or printed output of these is performed from an outputsection 109, which is an output device.

Object Attributes

Here, description is given using FIG. 4, regarding the structure ofattributes of object images contained in document data used in thepresent embodiment. It should be noted that description is givenfollowing the SVG (scalable vector graphics) format for object imagedata in the present embodiment in order to simplify description.

A color appearance accordance attribute (color_appearance_accordance)401 as shown in FIG. 4 is appended as an attribute of object images inthe present embodiment. Namely, in a case where the color appearanceaccordance attribute 401 is “ON,” indication is given to an effect thatthe object in question is to be output (displayed/printed) having acolor whose appearance accords with the target appearance color. Thatis, in a case where a same output color is specified for a plurality ofobject images in a document and the color appearance accordanceattributes of these are respectively “ON,” it is expected that theoutput of these objects will have the same appearance. In the presentembodiment, according to the indication of the color appearanceaccordance attribute 401, the objects 301, 302, and 303 shown in FIG. 3for example will be output using colors having a same appearance.

On the other hand, in a case where the color appearance accordanceattribute 401 is “OFF,” no particular color appearance accordanceprocess is carried out, and therefore the appearances of the objects301, 302, 303 will be influenced by the background color as shown inFIG. 3 for example in a same manner as conventionally, thus notnecessarily being in accord.

Object Attribute Information Obtaining Section 103

Next, detailed description is given regarding a process of obtainingobject attribute information in the object attribute informationobtaining section 103.

Of the object images contained in the document data input by the inputsection 101, the object attribute information obtaining section 103collects those whose attributes indicate that they are to be output soas to be a target appearance color, which is described later, that is,those whose aforementioned color appearance accordance attribute is ON.Then, an object information list is generated that describes a result ofthe collection.

FIG. 5 shows one example of an object information list generatedaccording to the present embodiment. In FIG. 5, the object informationlist is constituted by an object ID, an sRGB color value, which is theoutput color of the object, and information of the image region in thedocument. It should be noted that in FIG. 5, in order to simplifydescription, only the region information and display color are shown asitems in the object information list, but in fact other settings arealso necessary in giving consideration to such factors as clipping dueto overlaps between object images.

The object information list that has been generated is communicated tothe color appearance model forward conversion section 104, thesurrounding adaptive background color obtaining section 106, and thecolor appearance model reverse conversion section 107, thus aiming toachieve appearance color accordance for the object images in the list.

Color Appearance Model Forward Conversion Section 104

Next, detailed description is given regarding color appearance modelforward conversion processing in the color appearance model forwardconversion section 104.

The color appearance model forward conversion section 104 uses colorappearance model forward conversion to calculate target appearance colorvalues, which are targets of appearance colors for specified sRGB valuesas color information for object images listed in the object informationlist. An ordinary method can be applied as a conversion method.Hereinafter, a color appearance model forward conversion method isdescribed using a color appearance model such as CIECAM97s and CIECAM02.

First, an equation for converting from CIE1931 XYZ tristimulus values toan RGB color space of sensitivity to long, middle, and short wavelengthsfor aptly describing human chromatic adaptation can be given by thefollowing equation (1).

$\begin{matrix}{\begin{bmatrix}R \\G \\B\end{bmatrix} = {M_{{CAT}\; 02}\begin{bmatrix}X \\Y \\Z\end{bmatrix}}} & (1)\end{matrix}$

Mcat02 in equation (1) is a chromatic adaptation matrix, and detailsthereof are described in Publication CIE 159 and elsewhere, andtherefore further description is not included here.

For example, to calculate target appearance color values for certainsRBG values (sR, sG, sB), first CIE1931 XYZ values are calculatedcorresponding to the values (sR, sG, sB). Then, further still, using theaforementioned equation (1), conversion is performed to RGB values of acolor space of sensitivity to long, middle, and short wavelengths foraptly describing human chromatic adaptation.

Next, in the present embodiment, consideration is given to thebackground colors of the target appearance color in order to control anactual appearance of objects. First, an adaptation factor is set as Dindicating a device white, that is, a degree of adaptation to a displaydevice or a display white. In other words, the adaptation factor D is avalue that takes into account ambient light conditions and the like, anddetails thereof are described in Publication CIE 159 and elsewhere, andtherefore further description is not included here.

Then, when the device white is normalized at 100 and the RGB values ofthe adaptive white point are set as RwGwBw, prediction equationsexpressing appearance values RcGcBc are as follows:Rc=[100·D/Rw+(1−D)]R  (2)Gc=[100·D/Gw+(1−D)]G  (3)Bc=[100·D/Bw+(1−D)]B  (4)

Here, in the present embodiment, the device white is used as thebackground color of the target appearance color, and a reason for thisis described below. The target appearance color is perceived darkestwhen the background color is white, and therefore the following occurswhen employing the darkest color in the reproduction color as the targetappearance color. Namely, if the background color is a darker color thanthe device white, then a perceived color equivalent to the targetappearance color can be obtained when a darker color than thereproduction color of the target appearance color is reproduced on anoutput device. For this reason, by using the device white as thebackground color of the target appearance color, the reproduction coloron the output device becomes easier to achieve within the color range ofthe output device. Accordingly, it is suitable to use the device whiteas the background color of the target appearance color.

As described above, in the color appearance model forward conversionsection 104, the adaptive white RwGwBw, which is a parameter ofCIECAM02, is applied in the color appearance model forward conversionequations (2) to (4) using the adaptive factor D, which takes intoaccount ambient light conditions and the like, as the background color(device white). In this way, target appearance color values RcGcBcaccording to the present embodiment are calculated.

Surrounding Adaptive Background Color Obtaining Section 106

Next, detailed description is given regarding a process of obtaining asurrounding adaptive background color in the surrounding adaptivebackground color obtaining section 106.

Based on display region information in the object information list, thesurrounding adaptive background color obtaining section 106 obtains asurrounding adaptive background color that is influenced by adaptationof color perceived by humans based on pixel values of pixels around thepixel for each pixel in the object image display region. In the presentembodiment, for example, a low pass filter process is executed on theimage, which has undergone rendering in the rendering section 102 and isin a device independent color space, which is a color space notdependent on a device, thus generating an image having color values ofthe corresponding surrounding adaptive background color for each pixel.It should be noted that detailed description of this image generatingmethod is given by M. D. Fairchild in Color Appearance Models (2ndEdition), and therefore description is not included here. What isimportant here is that the low pass filter is required to haveproperties dependent on the observation distance and the viewing angleat which the display device or the printed output is observed, namely, aspatial frequency as viewed by an observer. That is, an image isgenerated having color values of the surrounding adaptive backgroundcolors using a low pass filter that gives consideration to thetwo-degree field of view or the ten-degree field of view prescribed bythe CIE.

Furthermore, a method in which the background color is obtained using atechnique of averaging the background region by determining a backgroundrectangular area for the pixel of interest dependent on a two-degreefield of view or a ten-degree field of view, and the observationdistance is known as another method of obtaining the surroundingadaptive background color. This method is commonly known, and thereforedescription is not included here.

By using one of the aforementioned methods or another method, thesurrounding adaptive background color obtaining section 106 obtainscolor values of surrounding adaptive background colors corresponding toeach pixel in the image that has undergone rendering in the deviceindependent color space.

Color Appearance Model Reverse Conversion Section 107

Next, detailed description is given regarding color appearance modelreverse conversion processing in the color appearance model reverseconversion section 107.

The aforementioned color appearance model forward conversion section 104has calculated a target appearance color, which is an appearance colortarget for the sRGB values, for object images having background color.The color appearance model reverse conversion section 107 calculates anactual color (hereinafter, reproduction color) so as to achieve thetarget appearance color. This is carried out by the color appearancemodel reverse conversion section 107 performing reverse conversion ofthe color appearance model executed by the color appearance modelforward conversion section 104.

Reverse conversion equations derived respectively from the equations (2)to (4) executed by the aforementioned color appearance model forwardconversion section 104 are shown below in equations (5) to (7).R=Rc/[100·D/Ra+(1−D)]  (5)G=Gc/[100·D/Ga+(1−D)]  (6)B=Bc/[100·D/Ba+(1−D)]  (7)

In equations (5) to (7), RcGcBc are target appearance color valuesobtained by the color appearance model forward conversion section 104.Furthermore, RaGaBa are color values of surrounding adaptive backgroundcolors corresponding to each pixel of an image obtained by thesurrounding adaptive background color obtaining section 106 for objectimages that have undergone rendering.

In order to calculate reproduction colors of object images to ensureaccordance in appearance colors, the color appearance model reverseconversion section 107 first obtains the appearance color target valuesRcGcBc determined by the color appearance model forward conversionsection 104. Next, region information of object images is obtained fromthe object information list determined by the object attributeinformation obtaining section 103, and surrounding adaptive backgroundcolors RaGaBa corresponding respectively to all the pixels contained inthe object image display region are obtained by the surrounding adaptivebackground color obtaining section 106. Then, using equations (5) to(7), output color RGB is obtained so as to enable output of the targetvalues RcGcBc of the appearance colors for all pixels contained in theobject image to achieve accordance in appearance colors.

The output colors RGB obtained here are converted to CIE XYZ valuesusing reverse conversion of equation (1), then further converted to sRGBvalues as display values in a device independent color space image.

Output Color Updating Section 108

Next, detailed description is given regarding a process of updating anoutput color of an object image region in the output color updatingsection 108.

As described above, the color appearance model reverse conversionsection 107 has calculated display sRGB values in the device independentcolor space image capable of achieving accordance in appearance colorsfor all pixels in the object images targeted for appearance coloraccordance. The output color updating section 108 writes the sRGB valuesof each pixel calculated by the color appearance model reverseconversion section 107 over the sRGB values of pixels corresponding tothe image that has undergone rendering by the rendering section 102 andis in the device independent color space.

It should be noted that the device independent color space image inwhich pixel values have been updated by the output color updatingsection 108 undergoes color matching in the output section 109 to adevice color space for display or printing, and is then displayed orprinted.

Color Conversion Processing in the Present Embodiment

FIG. 2A and FIG. 2B are a flowchart showing a color conversion processaccording to the present embodiment.

First, in step S201, the object image data to be processed is input bythe input section 101. Then, in step S202, a determination is performedas to whether or not rendering by the rendering section 102 has beencompleted for all the input object image data. If it is determined thatrendering has been completed, the procedure proceeds to step S206. Onthe other hand, if it is determined that rendering has not beencompleted, the procedure proceeds to step S203.

In step S203, the object attribute information obtaining section 103examines the attributes of object images being processed and if thecolor appearance accordance attribute is set to ON, the attributeinformation of the object images is saved in step S204, then theprocedure proceeds to step S205. On the other hand, if the colorappearance accordance attribute is OFF, then the procedure directlyproceeds to step S205.

In step S205, rendering is carried out on the object images by therendering section 102, and device independent color space images aregenerated. Then the procedure returns to step S201.

After rendering is completed (YES in step S202), the device independentcolor space images are obtained in step S206. Then, in step S207, theobject information list generated in step S204 is searched in order, anda determination is performed in step S208 as to whether or not the colorappearance accordance attribute is ON. If it is determined that thecolor appearance accordance attribute is not ON, then the processingreturns to step S207.

If it is determined that the color appearance accordance attribute isON, then next, in step S209, an output color and display region of theobject image is obtained from the object information list. In thefollowing step S210, color appearance model forward conversion isexecuted by the color appearance model forward conversion section 104 onthe output colors obtained from the object information list, thuscalculating target appearance color values. In step S211, surroundingadaptive background colors are obtained by the surrounding adaptivebackground color obtaining section 106 for each pixel of the objectimage display region based on the display region information of theobject information list.

Then, in step S212, display values are calculated by the colorappearance model reverse conversion section 107 for the deviceindependent color space image corresponding to all the pixels containedin the object image region. The reverse conversion calculates arecarried out based on the target appearance color values calculated bythe color appearance model forward conversion section 104, the colorvalues of the surrounding adaptive background colors obtained by thesurrounding adaptive background color obtaining section 106, and theimage region information in the object information list.

Then, in step S213, the output color updating section 108 overwrites allpixel values of corresponding pixels to output values of the deviceindependent color space image calculated by the color appearance modelreverse conversion section 107 for device independent color space imagesthat have undergone rendering.

When processing is completed in step S208 for all object images whosecolor appearance accordance attribute is ON, the procedure proceeds tostep S214. In step S214, the output section 109 executes color matchingon the device independent color space image to device-dependent colorspace values for display or printed output, after which display orprinted output is carried out, thus completing the present process.

As described above, with the present embodiment, in carrying outrendering on object data containing color data and drawing commands,color appearance model conversion is carried out giving consideration tothe background colors of the objects. Accordingly, it is possible toeliminate the influence of background color adaptation for a pluralityof objects respectively having a same output color specified within asingle sheet of a document and achieve accordance in appearance amongthese.

Detailed description was given above of an example embodiment, but thepresent invention is also achievable in embodiments such as a system, anapparatus, a method, a program, or a recording medium (storage medium).Specifically, it may also be applied to a system constituted by multipledevices (such as a host computer, an interface device, an image sensingapparatus, and a Web application) and may also be applied to anapparatus constituted by a single device.

It should be noted that the present invention may also be accomplishedby supplying directly or remotely a software program that achieves thefunctions of the foregoing embodiments to a system or an apparatus, andhaving a computer of the system or apparatus read out and execute thesupplied program code. It should be noted that “program” in this caserefers to a program that is computer-readable and corresponds to theflowchart shown in the figures pertaining to the embodiments.

Consequently, the actual program code to be installed on a computer toachieve the functional processing of the present invention on thecomputer achieves the present invention. That is, the present inventionalso includes an actual computer program for achieving the functionalprocessing of the present invention.

In this case the program may take any form and may be object code, aprogram to be executed by an interpreter, or script data supplied to anOS as long as it has the functionality of the program.

Recording media for supplying the program include the media shown below.For example, this includes floppy disks, hard disks, optical disks,magneto-optical disks, CD-ROM, CR-R, CR-RW, magnetic tape, nonvolatilememory cards, ROM, DVD (DVD-ROM, DVD-R) and the like.

The methods described below are also possible as methods for supplyingthe program. Namely, an actual computer program (or a compressed filecontaining an automatic installation function) of the present inventionmay be downloaded onto a recording medium such as a hard disk byconnecting to an Internet website via a browser on a client computer.

Furthermore, it is also possible to achieve the present invention byhaving the program code that constitutes the program of the presentinvention divided into a plurality of files and downloading therespective files from different websites. That is, a WWW server thatenables a plurality of users to download the program files for achievingthe functional processing of the present invention on a computer is alsoincluded within the present invention.

Furthermore, it is also possible to encode the program of the presentinvention for storage on a storage medium such as a CD-ROM, which isthen distributed to users, and users who pass a predetermined conditionmay be allowed to download from a website via the Internet informationof a key that decodes the encoding. That is to say, users who executethe encoded program by using the key information are able to install theprogram on a computer.

Furthermore, the functionality of the foregoing embodiment is achievedby having a computer execute the program that has been read out. Furtherstill, an OS or the like that runs on a computer may carry out a part orall of the actual processing according to instructions of the programsuch that the functionality the above-described embodiment is achievedby the processing thereof.

Further still, the program that is read out from the recording mediummay be written onto a memory provided in an extension board insertedinto the computer or an extension unit connected to the computer, afterwhich the functionality of the foregoing embodiments can be achieved byexecuting the program. That is, it is possible that a CPU or the likeprovided in the extension board or extension unit may carry out a partor all of the actual processing according to instructions of theprogram.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2007-259234, filed Oct. 2, 2007, which is hereby incorporated byreference herein in its entirety.

1. An image processing apparatus for converting an image having aplurality of objects, comprising: a rendering unit configured to performrendering on an image using object information of the plurality ofobjects; a forward conversion unit configured to carry out forwardconversion processing of a color appearance model on color informationof the object in which a pixel of interest is contained, and calculatetarget color information of the pixel of interest; a surroundingadaptive background color obtaining unit configured to generatesurrounding adaptive background color information of the pixel ofinterest based on pixels around the pixel of interest in the object ofthe image that has undergone rendering; a reverse conversion unitconfigured to carry out reverse conversion of a color appearance modelon the target color information based on the surrounding adaptivebackground color information to calculate output color information; anda setting unit configured to set the output color information as colorinformation of the pixel of interest in the image that has undergonerendering.
 2. The image processing apparatus according to claim 1,wherein the object includes a color appearance accordance attribute, andthe reverse conversion unit controls whether to calculate output colorinformation for the object in accordance with the color appearanceaccordance attribute of the object.
 3. The image processing apparatusaccording to claim 1, wherein the forward conversion unit calculates thetarget appearance color using white as the background color of theobject.
 4. The image processing apparatus according to claim 1, whereinthe surrounding adaptive background color obtaining unit uses a low passfilter corresponding to an observation distance and a viewing angle atwhich an output image is to be observed.
 5. The image processingapparatus according to claim 4, wherein the low pass filter hasproperties corresponding to a two-degree field of view or a ten-degreefield of view prescribed by CIE.
 6. The image processing apparatusaccording to claim 1, wherein the surrounding adaptive background colorobtaining unit generates the surrounding adaptive background color bydetermining a background rectangular area for the pixel of interestdependent on a two-degree field of view or a ten-degree field of view,and an observation distance, and averaging the background rectangulararea.
 7. The image processing apparatus according to claim 1, whereinthe reverse conversion unit of the color appearance model uses a samecolor appearance model as the color appearance model of the forwardconversion unit.
 8. An image processing method for converting an imagehaving a plurality of objects, the method comprising: a rendering stepof performing rendering on an image using object information of theplurality of objects; a forward conversion step of carrying out forwardconversion processing of a color appearance model on color informationof the object in which a pixel of interest is contained, and calculatingtarget color information of the pixel of interest; a surroundingadaptive background color obtaining step of generating surroundingadaptive background color information of the pixel of interest based onpixels around the pixel of interest in the object of the image that hasundergone rendering; a reverse conversion step of carrying out reverseconversion of a color appearance model on the target color informationbased on the surrounding adaptive background color information tocalculate output color information; and a setting step of setting theoutput color information as color information of the pixel of interestin the image that has undergone rendering.
 9. The image processingmethod according to claim 8, wherein the object includes a colorappearance accordance attribute, and in the reverse conversion step ofthe color appearance model, control is performed as to whether tocalculate output color information for the object in accordance with thecolor appearance accordance attribute of the object.
 10. Anon-transitory computer-readable storage medium storing a computerprogram, the computer program causing a computer to implement an imageprocessing method for converting an image having a plurality of objectscomprising: rendering on an image using object information of theplurality of objects; carrying out forward conversion processing of acolor appearance model on color information of the object in which apixel of interest is contained, and calculating target color informationof the pixel of interest; generating surrounding adaptive backgroundcolor information of the pixel of interest based on pixels around thepixel of interest in the object of the image that has undergonerendering; carrying out reverse conversion of a color appearance modelon the target color information based on the surrounding adaptivebackground color information to calculate output color information; andsetting the output color information as color information of the pixelof interest in the image that has undergone rendering.